Matthew Foley

Cerebral cavernous malformations arise from endothelial gain of MEKK3–KLF2/4 signalling

Cerebral cavernous malformations (CCMs) are common inherited and sporadic vascular malformations that cause strokes and seizures in younger individuals. CCMs arise from endothelial cell loss of KRIT1, CCM2 or PDCD10, non-homologous proteins that form an adaptor complex. How disruption of the CCM complex results in disease remains controversial, with numerous signalling pathways (including Rho, SMAD and Wnt/β-catenin) and processes such as endothelial–mesenchymal transition (EndMT) proposed to have causal roles. CCM2 binds to MEKK3 (refs 7, 8, 9, 10, 11), and we have recently shown that CCM complex regulation of MEKK3 is essential during vertebrate heart development. Here we investigate this mechanism in CCM disease pathogenesis. Using a neonatal mouse model of CCM disease, we show that expression of the MEKK3 target genes Klf2 and Klf4, as well as Rho and ADAMTS protease activity, are increased in the endothelial cells of early CCM lesions. By contrast, we find no evidence of EndMT or increased SMAD or Wnt signalling during early CCM formation. Endothelial-specific loss of Map3k3 (also known as Mekk3), Klf2 or Klf4 markedly prevents lesion formation, reverses the increase in Rho activity, and rescues lethality. Consistent with these findings in mice, we show that endothelial expression of KLF2 and KLF4 is increased in human familial and sporadic CCM lesions, and that a disease-causing human CCM2 mutation abrogates the MEKK3 interaction without affecting CCM complex formation. These studies identify gain of MEKK3 signalling and KLF2/4 function as causal mechanisms for CCM pathogenesis that may be targeted to develop new CCM therapeutics.

Micro-CT Imaging Reveals Mekk3 Heterozygosity Prevents Cerebral Cavernous Malformations in Ccm2-Deficient Mice

Mutations in CCM1 (aka KRIT1), CCM2, or CCM3 (aka PDCD10) gene cause cerebral cavernous malformation in humans. Mouse models of CCM disease have been established by deleting Ccm genes in postnatal animals. These mouse models provide invaluable tools to investigate molecular mechanism and therapeutic approaches for CCM disease. However, the full value of these animal models is limited by the lack of an accurate and quantitative method to assess lesion burden and progression. In the present study we have established a refined and detailed contrast enhanced X-ray micro-CT method to measure CCM lesion burden in mouse brains. As this study utilized a voxel dimension of 9.5μm (leading to a minimum feature size of approximately 25μm), it is therefore sufficient to measure CCM lesion volume and number globally and accurately, and provide high-resolution 3-D mapping of CCM lesions in mouse brains. Using this method, we found loss of Ccm1 or Ccm2 in neonatal endothelium confers CCM lesions in the mouse hindbrain with similar total volume and number. This quantitative approach also demonstrated a rescue of CCM lesions with simultaneous deletion of one allele of Mekk3. This method would enhance the value of the established mouse models to study the molecular basis and potential therapies for CCM and other cerebrovascular diseases.

Induction and Micro-CT Imaging of Cerebral Cavernous Malformations in Mouse Model

Mutations in the CCM1 (aka KRIT1), CCM2, or CCM3 (aka PDCD10) gene cause cerebral cavernous malformation (CCM) in humans. Mouse models of CCM disease have been established by tamoxifen induced deletion of Ccm genes in postnatal animals. These mouse models provide invaluable tools to investigate molecular mechanism and therapeutic approaches for CCM disease. An accurate and quantitative method to assess lesion burden and progression is essential to harness the full value of these animal models. Here, we demonstrate the induction of CCM disease in a mouse model and the use of the contrast enhanced X-ray micro computed tomography (micro-CT) method to measure CCM lesion burden in mouse brains. At postnatal day 1 (P1), we used 4-hydroxytamoxifen (4HT) to activate Cre recombinase activity from the Cdh5-CreErt2 transgene to cleave the floxed allele of Ccm2. CCM lesions in mouse brains were analyzed at P8. For micro-CT, iodine based Lugols solution was used to enhance contrast in brain tissue. We have optimized the scan parameters and utilized a voxel dimension of 9.5 µm, which lead to a minimum feature size of approximately 25 µm. This resolution is sufficient to measure CCM lesion volume and number globally and accurately, and provide high-quality 3-D mapping of CCM lesions in mouse brains. This method enhances the value of the established mouse models to study the molecular basis and potential therapies for CCM and other cerebrovascular diseases.

Non-destructive analysis on nano-textured surface of the vertical LED for light enhancement

In this work, the nano-textured surface of a GaN-based vertical light emitting diode (VLED) is characterized using a unified framework of non-destructive techniques (NDT) incorporating scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, Photoluminescence (PL), and X-ray diffraction (XRD) to optimize the light output efficiency. The surface roughness of ∼300 nm is revealed by AFM. Compressive stress-state of 0.667 GPa in the GaN surface is indicated by the E2(high) and A1(LO) phonon peak values at 569 cm-1 and 736 cm-1, respectively, in Raman spectrum and the wavelength at 442 nm rather 450 nm in PL spectrum. Without damaging the LED, surface analysis by NDT helps to advance the understanding of the optimized angular light redistribution subject to the high-roughness surface and the negative impacts of the stress induced at the top GaN layer, which leads to the optical efficiency degradation of the VLED. Furthermore, the impact of texturing on underneath n-GaN and MQWs layers is investigated via SEM-based transmission Kikuchi diffraction (TKD) and aberration-corrected scanning transmission electron microscopy (AC-STEM) and revealed a smooth surface morphology and good crystalline quality, indicating that the etch-induced damage by texture engineering does not impair the active region of the VLED. Accordingly, prospective optimizations are suggested in the context of surface engineering for light enhancement in VLEDs.

Physical properties of root cementum: Part 27. Effect of low-level laser therapy on the repair of orthodontically induced inflammatory root resorption: A double-blind, split-mouth, randomized controlled clinical trial

Introduction: The purpose of this 2‐arm‐parallel split‐mouth trial was to investigate the effect of low‐level laser therapy (LLLT) on the repair of orthodontically induced inflammatory root resorption (OIIRR). Methods: Twenty patients were included in this study, with 1 side randomly assigned to receive LLLT, and the other side served as a sham. Eligibility criteria included need for bilateral maxillary first premolar extractions as part of fixed appliance treatment. OIIRR was generated by applying 150 g of buccal tipping force on the maxillary first premolars for 4 weeks. After the active force was removed, the teeth were retained for 6 weeks. LLLT commenced with weekly laser applications using a continuous beam 660‐nm, 75‐mW aluminum‐gallium‐indium‐phosphorus laser with 1/e2 spot size of 0.260 cm2, power density of 0.245 W/cm2, and fluence of 3.6 J/cm2. Contact application was used at 8 points buccally and palatally above the mucosa over each tooth root for 15 seconds with a total treatment time of 2 minutes. After 6 weeks, the maxillary first premolars were extracted and scanned with microcomputed tomography for primary outcome OIIRR calculations. Subgroup analysis included assessment per root surface, per vertical third, and sites of heaviest compressive forces (buccal‐cervical and palato‐apical). Randomization was generated using www.randomization.com, and allocation was concealed in sequentially numbered, opaque, sealed envelopes. Blinding was used for treatment and outcome assessments. Two‐tailed paired t tests were used to determine whether there were any statistically significant differences in total crater volumes of the laser vs the sham treated teeth. Results: Total crater volumes were 0.746 mm3 for the laser treated teeth and 0.779 mm3 for the sham. There was a mean difference of 0.033 ± 0.39 mm3 (95% CI, −0.21 to 0.148 mm3) greater resorption crater volume in the sham group compared with the laser group; this was not statistically significant (P = 0.705). No harm was observed. Conclusions: No significant difference was found between LLLT and sham control groups in OIIRR repair. HighlightsThe effect of low‐level laser therapy (LLLT) on healing of root resorption was assessed on extracted teeth.Root resorption crater volumes were similar in the LLLT and sham teeth.No differences were found per vertical thirds and tooth surfaces.LLLT did not seem to influence root repair after orthodontic force cessation.

Corrigendum: Cerebral cavernous malformations arise from endothelial gain of MEKK3–KLF2/4 signalling

This corrects the article DOI: 10.1038/nature17178

Visualization of the structural changes in plywood and gypsum board during the growth of Chaetomium globosum and Stachybotrys chartarum

Fungal growth in indoor environments is associated with many negative health effects. Many studies focus on brown- and white-rot fungi and their effect on wood, but there is none that reveals the influence of soft-rot fungi, such as Stachybotrys spp. and Chaetomium spp., on the structure of building materials such as plywood and gypsum wallboard. This study focuses on using micro-computed tomography (microCT) to investigate changes of the structure of plywood and gypsum wallboard during fungal degradation by S. chartarum and C. globosum. Changes in the materials as a result of dampness and fungal growth were determined by measuring porosity and pore shape via microCT. The results show that the composition of the building material influenced the level of penetration by fungi as shown by scanning electron microscopy (SEM). Plywood appeared to be the most affected, with the penetration of moisture and fungi throughout the whole thickness of the sample. Conversely, fungi grew only on the top cardboard in the gypsum wallboard and they did not have significant influence on the gypsum wallboard structure. The majority of the observed changes in gypsum wallboard occurred due to moisture. This paper suggests that the mycelium distribution within building materials and the structural changes, caused by dampness and fungal growth, depend on the type of the material.

EDP2XRD: a computer program for converting electron diffraction patterns into X-ray diffraction patterns

Mny commercial software packages for X-ray diffraction pattern analysis are capable of identifying multiple phases in bulk materials. However, X-ray diffraction patterns cannot record those phases with very small volume ratio or non-homogeneous distribution, which may mean that researchers have to use instead electron diffraction patterns from a very small region of interest. EDP2XRD, a new program for converting electron diffraction patterns into X-ray diffraction patterns, is described here. The program has been developed in order to utilize X-ray analysis software for electron diffraction patterns taken from mixed-phase nanocrystalline materials with a transmission electron microscope. It is specifically designed for material researchers who are engaged in crystallographic microstructure analysis. The difference from other popular commercial software for crystallography is that this program provides new options to convert and plot X-ray diffraction patterns for arbitrary electron diffraction rings and to process raw images to enhance conversion performance. The program contains the necessary crystallographic calculator to list planar d spacings and corresponding X-ray diffraction angles.

Fabrication of gold-based fractal surfaces

A novel method for fabrication of complex gold nanostructures is presented. Fractal aggregations of ethylenediaminetetraacetic acid (EDTA) chelates formed in seconds during solvent evaporation are used as masks for gold plating. SEM analysis shows evidence of general features on several scales from 100 μm down to considerably less than 100 nm with complete metal coverage.